Learning about functions QAQ

Function definition and call

Definition ： utilize def Function name （）： The format of
For function calls , Write the function name directly （） that will do .

Functions with parameters

Write directly in the parentheses of the function name .

Function with return value

return
It can print directly , You can also use a variable to receive , Printout in progress .

Multiple functions that return values

stay return You can then write multiple return values , When receiving the return value , Just write the variable names in order .

Small exercise

Print single line

Write a function that prints a horizontal line

def printinfo():
    print("----------")
printinfo()

Print custom number of lines

# Write a function , You can use the input parameters , Print out the horizontal line of the custom number of lines

def printinfo():
    print("----------")
def printinfos(num):
    # i = 1
    # while i <= num:
    # printinfo()
    # i += 1
    for i in range(0, num):
        printinfo()
num = int(input(" Please enter the number of pieces to print ："))
printinfos(num)

Sum three numbers

Write a function to find the sum of three numbers

def add(a,b,c):
    sum = a + b + c
    print(sum)
add(1,2,3)

averaging

Write a function to find the average of three numbers

def add(a,b,c):
    sum = a + b + c
    return sum
def avg():
    a = add(1,2,3)
    num = a/3.0
    print(num)
avg()

Local and global variables

local variable

The scope of a local variable is in the body of the function that defines it , Leaving the function body scope ends .
Traversal with the same name can be defined in functions that are not used , They don't influence each other .

Global variables

The global variable scope is the entire file .
Can be used by all functions .

Global variables and local variables use the same variable name

When global variables and local variables are defined with the same variable name , In a function that defines a local variable , Local variables are preferred , Functions that do not define variables use global variables .

Function to change the value of a global variable

Use global Add variable names to declare global variables , Then you can modify the global variables .